The present invention relates to a process for the preparation of pyrazines, more particularly trialkyl pyrazines which are useful in food applications.
Alkyl pyrazines are important flavour components which are formed during the cooking of many kinds of foods. Generally, they impart roasted or burnt aromas to cooked foods. There is an expectation of an increase in the usage of alkyl pyrazines in the food industry, especially in the booming market of microwaveable foods.
The formation of alkyl pyrazines in foods has been extensively studied using carbohydrate-ammonia model systems. But these types of reactions always give a complex mixture of products with low total yields.
Chiu, et al., J. Agric. Food. Chem. 38, 58-61 (1990) describe an investigation of the effect of long chain aldehydes on the formation of long-chain alkyl-substituted pyrazines in model systems of acetol (hydroxy acetone-a 1-hydroxy-2-ketone) and ammonium acetate (known precursors of pyrazines in food systems) with and without the addition of pentanal or hexanal (well known degradation products of lipids). However, it has been found that the yields of the trialkyl pyrazines are only of the order of about 0.5%.